For most online merchants, it's a simple equation: the higher they rank in search engines, the more shoppers they attract.

Given that all-important formula, many e-tailers lose sleep wondering one pressing question: how can I increase my search engine presence? How can I boost my ranking on as many search terms as possible?

They know that simply submitting their site to Google and Yahoo and then expecting a high ranking is like waiting for rain in the desert. Yeah, it might show up. Someday.

Of course, many merchants pay for high visibility on certain keywords — spending a fortune on pay-per-click advertising. But the real goldmine, the true sweet spot, is getting a high organic (that is, unpaid) search ranking.

That's hard to do. It's a crowded online marketplace, and the search engines use a complex — and secret — algorithm to determine ranking, constantly tweaking it to avoid being tricked. It's not like the old days, when you could hide the word "sex" in your meta tags and drive hordes of users to your site about lawn mowers.

At this point, you need real expertise (or a whole lot of time) to get a high organic ranking. Knowing this, many merchants hire search engine optimization experts to review their site and direct changes in hopes that it'll improve their ranking.

But whom do you hire? Since SEO is a young field, it's hard to know the good practitioners from the quacks. We've all gotten spam like: "Guaranteed Top 10 Ranking in 30 Days! Try MegaBuckSEOGenius.com! Just $79!"

It's even possible that a vendor honestly thinks he or she is an SEO expert, but hasn't kept up with the ever-changing search engine tactics. Using last year's techniques won't optimize performance.

Even among legitimate experts, it's hard for a merchant to make a choice. The fees range wildly, and a higher price doesn't always buy more expertise. How much should merchants expect to pay? And what, exactly, should they expect an SEO firm to actually do?

Grifters Galore
There is no regulatory agency that oversees SEO firms. Any 14-year-old with a Web site can put out a shingle and call himself an SEO expert (and that teen might be better than some of the self-proclaimed experts.)

The SEO business has more scam artists than most industries. The scammers "are definitely out there — they're everywhere," says Jamie Low.

"In the last two years there's been a huge saturation in the market, with people who just saw where the money is and started saying they offer search marketing services, and they're kind of figuring it out as they go."

One warning signal of a firm to avoid: "It's the firms who send out mass pitches," says Danny Sullivan. "It's fair to say that it's the rare good SEO firm that is overtly going out there and sending you [junk] e-mail — those services tend not to be very good at all."

"The ones you get in your spam box aren't even the people I would worry about," Low says; they're easy to spot as a poor choice. "The people I'd worry about are the ones who give a sense of being professional — it's the sales people who don't know exactly how the whole thing works."

Jill Whalen points out, "The problem with this field is that anyone can read enough articles and talk a good game — it's easy to talk about it, but actually doing and making it work is so much harder."

"You'll get these companies that will get your site ranked highly for keyword phrases, and they can show you past clients where they've ranked them highly for keyword phrases. But what you don't know as a small business consumer is that those phrases are not being searched for by people, so you may get those rankings but no traffic or sales from them," she adds.

This irrelevant search term ranking is probably the most prevalent 'scam,' Whalen says. "Not that those people are necessarily trying to scam anyone but you end up feeling, 'What did I just throw my money away for?'"

On the other hand, sometimes clients bring on problems themselves by trying to achieve too much. "They'll say, 'I want to be found for 'homes,' and they'll find an SEO who'll say 'Okay, we can do that,' even though there's no way they can do that."

"It's unfortunate that many SEO companies aren't honest and say 'No, we can't do that — and it's not necessarily what you really want us to do,'" she says.

"I'll turn them down, but then they'll just go to someone else who'll tell them exactly what they want to hear."

"You don't find offers of guaranteed placement from most of the reputable firms," says Brad Fallon. "Almost to affirm it, they'll say, 'We can't guarantee results - and anyone that would is a charlatan.'"

Notes Sullivan: "A good company, first of all, knows that they can't guarantee that they'll get you into the top page of results. Nobody can do that. They can work, and make changes, and that might very well be what happens, and certainly pricing might be based on what's achievable in the end."

"But a really good company will be stressing that it's not that they get you on the page for any specific result, it's that they're going to be driving you traffic that's going to drive you sales."

However, Sullivan points out an exception to the 'no guarantee' rule: if you want to be found for an extremely specific term. An SEO firm "can get you on the first page of search results if you don't mind the fact that you're showing up for 'east Michigan kitchen supplies for small kitchens.'" But of course such a narrow niche might not be valuable (then again, it might be excellent, depending on your business).

Another red flag to watch out for, "is firms that won't tell you what they're going to do," says Fallon. "Be wary of the 'black box' — like, 'We have all these magic secrets, and if you pay us a bunch of money we'll use them, but we can't tell you what they are.'"

"They should be able to tell you exactly what they're doing, and how much the cost is for various parts of the service."

Adding confusion, not only are there 'black hat' and 'white hat' methods of SEO, there are also 'gray hat' methods, Low notes. These are techniques that aren't exactly unethical, but they're short term and produce little real gain.

"If you run into a situation where the vendor is trying to do anything that is deceptive in any way, shape or form, where they're trying to deliver something the user is never going to see [like hidden keywords] then that's not a path you want to do down."

One of the tricks of unscrupulous SEO firms is to take their client's money and spend part of it on some form of paid search - without their client's knowledge.

Traffic begins to increase quickly, of course. However, "all of a sudden you're paying these fees, but you're not really realizing who you're paying," Low says. And the very day the merchant stops paying, traffic starts to fade. The SEO firm seems to have them in a vise grip: either keep paying us, or your search engine presence will disappear.